In this situation, silence truly is extraordinary. When Michelle Rhee was chancellor of D.C. schools, her teacher firings triggered street demonstrations organized by multiple unions and contributed greatly to the defeat of the mayor, Adrian Fenty, who appointed Rhee. The firings were the major reason Rhee stepped down.

What changed in only a half-dozen months?

A small part of the change can probably be attributed to the contrasting personalities between Henderson and Rhee. The two women are friends -- just before Rhee took the job, she made Henderson vow to a "pinkie oath" to join her at District of Columbia Public Schools -- and they share a similar educational strategy for turning around D.C. schools. But while Rhee never ducked the spotlight and always cast her reforms as a national crusade (We are going to reform urban education in this country!), Henderson barely stirs up a media ripple.

It also doesn't hurt that Henderson is African-American, the same race as most of the teachers, parents, and students. The fact that Rhee, a Korean-American, was making visible progress with schools that a string of African-American schools chiefs had not, never went over well in this race-conscious town.

But something else, something much bigger, explains this silence. With a sudden and striking momentum that nearly defies explanation, states are redefining their expectations for teachers. Ohio, Illinois, Nevada, Utah, Florida, Indiana, Idaho, Arkansas, and Michigan are on that list. Last year Colorado weighed in with dramatic reforms, and parallel reforms are expected soon in New Jersey and Texas. D.C. no longer stands alone. The reforms vary by state, but the common themes are clear. Teachers are expected to prove they are effective before being awarded the job protections of tenure. They are expected to undergo serious job evaluations that include both classroom observations and student test scores. When kicked out of one school for being ineffective, they don't necessarily have a guaranteed job in another school. And in a few cases, they are no longer rewarded financially for mere longevity and university degrees that have no connection to improving teaching skills.

Critics of these changes predict fallout from veteran teachers opting for early retirement and would-be teachers seeking other career paths. Perhaps. But it's also possible we are witnessing the opening moves of a badly needed correction.

For many years now, the best and brightest U.S. women have experienced a blossoming of career opportunities, most of them jobs that command respect in both salaries and prestige -- unlike teaching. At the same time, men continue to shun teaching, more than ever.

Mix those trends together and the result is a teaching force that tends to be recruited from the bottom tier of college students. In countries that consistently outperform the United States, just the opposite happens. The logic behind this recent surge in education reforms: If the best and brightest are going to return to teaching in this country, they must be treated like other professionals, where success is both recognized and rewarded.

What Rhee and Henderson learned in D.C., and what other urban superintendents will tell you in an unguarded moment, is that this trend manifests itself most starkly in the nation's urban schools, the very schools that most need the brightest and most motivated teachers to push back against the staggering learning challenges many poor children bring into schools.

True, there are high-performing urban school districts that don't need to turn over their teaching staffs to boost student progress. Long Beach, CA. for example, has a teaching corps many high-performing suburban districts would die for. But if you're a parent in St. Louis, Baltimore, Detroit, Newark, Los Angeles, Kansas City (the list goes on) and your superintendent says there's no need to bring in teachers with sharper skills and higher expectations, well, I'd start lobbying for a new schools chief.

In the United States, teachers are rarely fired for being ineffective teachers. A few school districts have tried. Los Angeles and New York City come to mind. But those efforts were swamped by the tight protections granted teachers unions that have the luxury, in many cases, of electing their own contract negotiators. It wasn't even a close contest.

But in D.C. we're seeing Rhee's strategy, holding poor teachers accountable for doing their jobs while rewarding the best teachers, play out over time. Based on my reporting, that strategy appears to be paying off. Not all schools improved under Rhee, but the ones that did, to varying degrees, swapped in better teachers.

Given the reform momentum in other states, the controversial Rhee reforms no longer look so controversial. Which explains why Henderson's firings, an act once considered educational heresy, were greeted mostly with silence.

Perhaps the correction has commenced.

Richard Whitmire is author of The Bee Eater: Michelle Rhee Takes On The Nation's Worst School District.